In a charged particle beam apparatus provided with a camera device, an optical image of a sample placed on a sample table is acquired by the camera device, and a position and a range on the sample to be observed can be selected on the optical image of the acquired sample by irradiating with a charged particle beam. In order to select the position and the range with high accuracy, it is required to adjust alignment of the optical image and a sample stage moving the sample table with high accuracy.
In JP-A-2010-198998 (PTL 1), an adjustment guide for recognizing the sample table having the same shape as the sample table in order to identify the size of the sample table in the optical image is displayed on a display screen on which the optical image of the sample table or the sample imaged by the camera device and is displayed, and on the display screen, the adjustment guide is enlarged or reduced or moved so as to coincide with the optical image of the sample table on the display screen, so that the size and center position of the sample table on the optical image are recognized. From correspondence between the recognized size of the optical image of the sample table on the display screen and the actual size of the sample table stored in advance, an enlargement magnification of the optical image acquired by the camera device and the center position of the sample table on the optical image are computed to adjust the alignment of the sample stage and the optical image.